I vote on 3 for every 5 posts I read. I vote on 1 of every 5 comments I read.

I use neither. I think the boo-vote is harmful to the system. I would probably use anti-kibitzer if it was integrated into the site.

-4 for each, but I usually read them anyway.

For posts I look for any of the following: new or interesting content; old content presented well; grammar, spelling, organization. I will vote more frequently on subjects I know or find more interesting. Comments I look for relevance to ongoing discussion; insights that provide better perspective; civility.

I expect that "fluff" or unwarranted assumptions affect my decisions negatively. Unskimmable posts are less likely to be read. Passive-aggressive pandering to the group annoys me a great deal, but mostly on a subconscious level.

I generally think along these lines: "Should I upvote this?" I rarely think "Should I downvote this?" I only downvote if I have a negative gut reaction to the post and cannot talk myself into upvoting. This plays out as my mind saying, "Downvote! Downvote! Downvote! Well, wait, should I upvote?"

I will reply with an explanation if one is asked for or I am downvoting for an unusual reason. I have sent private messages explaining downvotes that I considered relevant to the post but off-topic (i.e. formatting or grammar issues). I have never given an explanation for upvoting.

Giving the poster/commenter feedback on their post/comment and drawing positive/negative attention to the post/comment.

Separate numbers for up and down votes. The ability to hide names with a reveal option similar to spoiler mouseovers. I would also like to see overall statistics on my karma and votes. Another potential feature is an option to actively vote 0.

If I reply to a comment I would normally downvote I will wait until a response is given before making the final decision. If I upvote and reply and later find out the reason I upvoted was ill-founded I will remove the upvote.

I take an upvote as "do more of this" and a negative as "something went wrong." No votes means "this comment was not useful."

I think that the concept of voting on a comment to push it toward a particular score is extremely harmful. Voting should be independent of a post/comment's current score.